Cooling device for vacuum treatment device

ABSTRACT

A cooling system for a vacuum processing apparatus is provided with an internal heat conduction path for transfer of heat entering the subject body through the vacuum processing apparatus, a heat radiation path for radiation of the heat to an outside of the vacuum processing apparatus and a heat conduction path for regulation of quantity of heat transfer between the internal heat conduction path and the heat radiation path. Preferably, a heat pipe is applied to the internal heat conduction path.

TECHNICAL FIELD

The present invention relates to a cooling system for cooling a subjectbody to regulate a temperature of the subject body in the course of asurface treatment process utilizing vacuum.

BACKGROUND ART

To improve physical or chemical properties or add novel functions,various surface treatments on subject bodies utilizing vacuum arepopularly practiced. As the surface treatments, film deposition, surfacemodification, surface nitriding, surface carbonization or carburisation,dry etching and such can be exemplified. The film deposition can befurther categorized into two categories of so-called “Physical VaporDeposition” (PVD hereinafter), in which film is grown under a physicalprocess such as vacuum evaporation, and “Chemical Vapor Deposition” (CVDhereinafter), in which film is grown under a chemical process, ingeneral. The surface treatments are processed with utilizing plasma incertain cases and CVD utilizing plasma is called “Plasma CVD”.

The surface treatments utilizing vacuum employs vacuum processingapparatuses which have constitutions preferable to the respectivetreatments. FIG. 7 schematically shows a vacuum processing apparatus100.

The vacuum processing apparatus 100 is provided with a chamber 102, theinterior of which is evacuated and then applied to a surface treatment,and a cooling system 104. The apparatus may be further provided with aheater, not shown in the drawings, for supplementary heating of asubstrate. The cooling system 104 absorbs heat entering the substratevia a heat absorption portion 104A. The absorbed heat is conducted via aheat transfer portion 104C to a heat radiation portion 104B as indicatedby an arrow AR10. The heat radiation portion 104B is provided with awater-cooling jacket 104D and the heat is radiated thereby so that thesubstrate is cooled.

FIG. 8 is a schematic drawing of a vacuum processing apparatus 120according to another example. It has a similar constitution as theaforementioned example though heat conduction in a cooling system 124 isdone by means of a cooling medium circulating therein.

DISCLOSURE OF INVENTION

One of technical problems of the prior vacuum processing apparatuses 100and 120 is how properly regulating the temperature of the substrate.Supplied energy for surface treatment, such as heat injected intoingredient gases or plasma, may be changed as necessary and hence theheat entering the substrate is changed in each case. Radiation heatradiating to the substrate may also vary according to constitutions ofauxiliary equipments housed in the chamber 102, and the same is true ina case of radiation heat radiating from the substrate. The temperatureof the substrate depends on a balance among the aforementioned heats,the supplementary heat applied by the heater and heat drained by thecooling system 104.

In a case where the injected heat is relatively large, the supplementaryheat by the heater comes to be nearly unnecessary so that the heatercannot effectively regulate the temperature of the substrate. On theother hand, the constitution of the cooling system 104 is uneasy to bechanged so as to change the amount of heat draining therefrom. Thisleads to a complication of the constitution of the cooling system 104 soas to allow replacement of members thereof and further makes work on thereplacement significantly laborious. More specifically, the prior vacuumprocessing apparatus has a problem of deficiency of controllabilityconcerning with the substrate temperature.

The present invention is achieved in view of the above problem andintended for providing a cooling system for a vacuum processingapparatus, which can properly regulate a temperature of a subject bodythough simply constituted.

According to a first aspect of the present invention, a cooling systemis provided with a heat pipe for transfer of heat entering a subjectbody which is treated with a vacuum treatment. Preferably the heat pipeis provided with a heat collection member. More preferably the heatcollection member is surface-treated so as to have a larger radiationcoefficient.

According to a second aspect of the present invention, a cooling systemfor a vacuum processing apparatus is provided with an internal heatconduction path for transferring heat entering a subject body, a heatradiation path for radiation of the transferred heat to an outside ofthe vacuum processing apparatus and a heat conduction path forregulation of quantity of heat transfer between the internal heatconduction path and the heat radiation path. Preferably, the heatconduction path is provided with a wall member, which isolates the innerheat conduction path and the heat radiation path so as to form a space,and a fluid regulation unit, which controllably fills a fluid for heatconduction into the space. More preferably, the fluid is gas. Furthermore preferably, the gas is one or more gases selected from a group ofgases having high heat conduction coefficient. Still further preferably,the heat conduction path is so configured as to have 1/10 or less of theheat transfer quantity when the space is vacant compared with the heattransfer quantity when the space is filled with the fluid. Additionallypreferably, the wall member is provided with an inner surface having aradiation coefficient of 0.7 or less. More preferably, an inner surfaceof the wall member is surface-treated so as to have a radiationcoefficient of 0.7 or less. Further more preferably, the inner heatconduction path is provided with a heat pipe.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of a cooling system and a vacuumprocessing apparatus according to a first embodiment of the presentinvention;

FIG. 2 is a schematic drawing of a heat radiation path according to afirst modification of the first embodiment of the present invention;

FIG. 3 is a schematic drawing of a heat radiation path according to asecond modification of the first embodiment of the present invention;

FIG. 4 is a constitution of a space for heat transfer of the coolingsystem according to the first embodiment of the present invention;

FIG. 5A is a constitution of a heat transfer space according to anotherembodiment, showing a state where liquid fills the heat transfer spacehalfway;

FIG. 5B is the heat transfer space of the aforementioned anotherembodiment, showing a state where liquid completely fills the heattransfer space;

FIG. 6 is a schematic drawing of a cooling system and a vacuumprocessing apparatus according to a second embodiment of the presentinvention;

FIG. 7 is a schematic drawing of a cooling system and a vacuumprocessing apparatus according to a prior art; and

FIG. 8 is a schematic drawing of a cooling system and a vaccumprocessing apparatus according to another prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the present invention will be describedhereinafter with reference to FIG. 1. FIG. 1 shows a vacuum processingapparatus 1 preferably applied to deposition of a thin film such as ana-Si film on a subject body formed in a plate like shape for example.

When depositing the thin film, a chamber 5 of the vacuum processingapparatus 1 includes ingredient gas in a depressurized state, forexample, at less than 1000 Pa. Electricity is supplied thereto so as togenerate plasma. A subject body W1 is closely attached to and supportedby a holder 9 and receives heat input AR1 from the plasma. Againstheating by the heat input AR1, the subject body W1 is cooled by thecooling system 3 so as to be a proper temperature. To give preferablequality to the thin film deposited on the subject body W1, it is animportant technical problem to properly regulate the temperature andcontrol a state of the plasma.

The cooling system 3 is provided with an inner heat conduction pathcomposed of a heat pipe 7 so as to conduct the heat AR1 received by thesubject body W1. One end 7A of the heat pipe 7 is thermally connected tothe holder 9 and the other end 7B is thermally connected to one end 11Aof a cooling member 11. The holder 9 and the cooling member 11 are madeof any material having high thermal conductivity such as metal so as toeffectively conduct heat.

The cooling member 11 is further provided with a heat radiation path 12connecting with an outside of the vacuum processing apparatus 1. Throughthe heat radiation path 12, a cooling medium such as cooling water flowsas indicated by an arrow AR2 in FIG. 1. The heat received by the end 7Aof the heat pipe 7 is conducted via the heat pipe 7 to the coolingmember 11 and radiated from the heat radiation path 12.

Alternatively, the heat radiation path 12 can be constituted inaccordance with a modified example shown in FIG. 2 or 3.

A heat radiation path 12A according to a first modification shown inFIG. 2 is provided with a heat transfer member 21 penetrating a vacuumpartition wall 5A composing the chamber 5 of the vacuum processingapparatus 1. One end 21A of the heat transfer member 21 is thermallyconnected to the cooling member 11. The other end 21B is thermallyconnected to a cooling medium such as water, oil and such. The heatconducted from the subject body is conducted via the heat pipe 7 and thecooling member 11 to the end 21A and then extracted via the heattransfer member 21 by the cooling medium.

A heat radiation path 12B according to a second modification shown inFIG. 3 is provided with a heat transfer member 23 penetrating the vacuumpartition wall 5A composing the chamber 5 of the vacuum processingapparatus 1. One end 23A of the heat transfer member 23 is thermallyconnected to the cooling member 11. The other end is provided withcooling fins 23B. The heat conducted from the subject body is conductedvia the heat pipe 7 and the cooling member 11 to the end 23A and thenradiated via the heat transfer member 23 by the cooling fins 23B.

According to any of the aforementioned modifications, a cooling mediumfor extraction of heat does not flow through the chamber 5. Thereby,when the thin film deposition is completed and hence cooling becomesunnecessary, possibility of unintended cooling of the interior of thechamber 5 by the cooling medium is reduced.

As shown in FIG. 1, the interior of the cooling member 11 is providedwith a heat transfer space 13 which is partitioned and substantiallyclosed by walls 13A and 13B. Functions as a control element such as aswitch for heat conduction, which turns the heat conduction on and off,a heat conduction variable resistance for controlling quantity of theheat transfer and such may be added to the heat transfer space 13. Gasor liquid fluid is filled into the heat transfer space 13. The heatconducted from the heat pipe 7 is conducted via the heat transfer space13, in which the fluid is filled, to the end 11B.

The heat transfer space 13 is thermally connected to a fluid controlunit 15 from which the fluid is injected. The fluid control unit 15controls an amount and/or a pressure of the fluid so as to function as aheat conduction switch which turns heat conduction on and off.Meanwhile, when the fluid control unit 15 is operated so as to controlvariation and/or the pressure of the fluid, the fluid control unit 15can control the heat flow passing through the heat transfer space 13. Inthis case, the heat transfer space 13 functions as a variable resistanceto heat conduction.

Quantity of the heat transfer between the walls 13A and 13B can bechanged dependently on thermal conductivity, which is determined by thecross-sectional area and the length of the heat transfer space 13, thecoefficient of heat conductivity and the pressure or the volume of thefluid filled therein.

In view of improvement of controllability of the heat flow, certainadvantages are given by a constitution in that a ratio of a heattransfer quantity when the heat transfer space 13 is filled with thefluid to a heat transfer quantity when the heat transfer space 13 isvacant is made larger. A heat transfer ratio is preferred to be smaller,preferably 1/10 or less and more preferably 1/20 or less, where the heattransfer ratio is defined as a ratio of a heat transfer quantity whenthe heat transfer space 13 is vacant to a heat transfer quantity whenthe heat transfer space 13 is filled with the fluid.

The heat transfer space 13 can be designed so that the heat transferratio is regulated to be an appropriate value by properly determining agap d of the heat transfer space 13, respective radiation coefficientε₁, ε₂ of the wall member 13A, 13B and a thermal conductivity k of thefluid filled therein. Calculation of heat transfer will be demonstratedhereinafter, in which the heat transfer quantity is calculated as avalue divided by a unit area, namely, as a heat flux. For example, whenthe temperature of the wall member 13A is 150 degrees C. and thetemperature of the wall member 13B is 200 degrees C., and provided thatthe gap d of the heat transfer space 13 is 2 mm and hydrogen gas (k=0.2W/mK in approx.) is filled therein at an enough pressure, the heat fluxis k×(200-150° C.)/d=5000 W/m². Meanwhile, when the heat transfer space13 is vacant, the heat flux can be calculated on the basis of proximityin which the heat is conducted only by radiation of the wall members13A, 13B. Therefore, supposing the radiation coefficients ε₁=ε₂=0.4, theheat flux becomes 250 W/m². Thus the heat transfer space 13 can bedesigned so that the heat transfer ratio is 1/20.

Either gas or liquid can be applied to the fluid. FIG. 4 shows anexample of a constitution to which a gas is applied.

The heat transfer space 13 is filled with gas supplied from the fluidregulation unit (gas regulation unit) 15. Any metal such as an In—Gaeutectic alloy, which is liquid at the working temperature, can bepreferably applied to the fluid. In a case where the liquid incompletelyfills the heat transfer space 13 as shown in FIG. 5A, the heat transferbecomes relatively low. In a case where the liquid completely fills theheat transfer space 13 as shown in FIG. 5B, the heat transfer becomesrelatively high. Thereby switching the heat transfer or regulating theheat transfer quantity can be achieved by means of properly regulatingthe amount of the liquid filling the heat transfer space 13 with thefluid regulation unit 15.

An operation of the cooling system 3, in accordance with a case wherethin film is deposited on a planar subject body W1 in the vacuumprocessing apparatus 1, will be described hereinafter. In the followingdescription, an example in which the heat transfer space 13 is filledwith hydrogen gas is given.

During depositing thin film, as shown by an arrow AR1 in the drawing,heat enters the subject body W1 in surface-contact with and supported bythe holder 9. The entering heat is conducted via the holder 9 to the end7A of the heat pipe 7 and further conducted via the heat pipe 7 to theother end 7B.

Subsequently the heat is conducted from the other end 7B to the end 11Aof the cooling member 11 and further conducted to the hydrogen gasfilling the heat transfer space 13. The heat is further conducted to theother end 11B of the cooling member 11 and cooled by a cooling mediumshown as an arrow AR2.

When completing the thin film deposition, the hydrogen gas is removedfrom the heat transfer space 13 by means of the fluid regulation unit 15so that the resistance of the heat transfer space 13 to the heat flux isincreased.

Subsequently, before disposing a next subject body to the holder 9 inthe chamber 5, the interior of the chamber 5 is heated up to atemperature which is proper to the thin film deposition. The temperatureof the holder 9 is immediately raised since the cooling system 3 iscomposed of the heat pipe 7 so as to have a small heat capacity and theresistance of the heat transfer space 13 to the heat flux is increased.Furthermore, because the resistance of the heat transfer space 13 to theheat flux is increased, even if the cooling medium shown as the arrowAR2 keeps flowing, the cooling medium is not obstructive to thetemperature increase of the holder 9. Additionally, the cooling mediumdoes not excessively cool the end 11A of the cooling member 11, therebyenergy consumption in a standby state can be suppressed.

When the chamber 5 is heated up to the proper temperature, the heattransfer space 13 is filled with hydrogen gas and the thin filmdeposition and the cooling are repeated.

According to the cooling system 3 of the first embodiment, thetemperature of the subject body can be properly regulated with such asimple constitution. Because of the simple constitution, when performingmaintenance of the vacuum processing apparatus 1, uninstallation andinstallation of the cooling system 3 can be easily performed.Additionally the temperature of the subject body W1 can be immediatelyand properly regulated because the heat pipe 7 is employed.

Furthermore, because efficiency of cooling can be regulated by means ofproper regulation of the gas in the heat transfer space 13 by the fluidregulation unit 15, the temperature of the subject body can be properlyregulated independently of heat quantity input to the subject body.Thereby quality of the thin film can be improved.

Additionally, the holder 9 can be disposed in a vertical or slantedposition though the holder 9 is disposed in a horizontal positionaccording to the aforementioned cooling system 3, however, the coolingmember 11 is preferably disposed in an upper position of the holder 9because the heat pipe is suitable to heat conduction in a verticaldirection.

In addition, to increase the resistance of the heat transfer space 13 tothe heat flux, pressure of the gas filled therein may be decreased sothat so-called molecular flow state in which mean free path of the gasis larger than sizes of the heat transfer space 13 is obtained.

Moreover, to further increase the resistance of the heat transfer space13 to the heat flux, the wall member 13A, 13B, at least the innersurfaces thereof, may be surface-treated so as to have a smallerradiation coefficient. As such surface-treatments, coating by means ofplating, ion-plating and such, or surface finishing such as finishing soas to decrease surface roughness, buffing, electrolytic polishing andsuch are preferable. Lowering the radiation coefficient results inincreasing controllability of the heat flux and hence the radiationcoefficient is preferably 0.7 or less and more preferably 0.4 or less.

A cooling system 33 and a vacuum processing apparatus 31 will bedescribed hereinafter with reference to FIG. 6. Constituent elementssubstantially identical to the elements of the cooling system 3 and thevacuum processing apparatus 1 of the aforementioned first embodiment isreferred as the same reference numerals and the detailed descriptionwill be omitted.

According to the present embodiment, the subject body W1 is disposeddistantly from a heat pipe 37. The heat pipe 37 is provided with a heatcollection member 39 which is configured so as to effectively absorbheat AR6 by means of heat transfer and/or radiation via the gas in thevacuum processing apparatus 31.

For effective absorption of the heat AR6, the heat collection member 39may be properly surface-treated so as to have a larger radiationcoefficient. As such surface treatments, oxidation, nitriding, aluminumanodization, blasting, proper coating, spraying such as Al₂O₃, platingsuch as chromia, ceramics coating and such are preferable.

The subject body W1 and the heat collection member 39 are disposed inparallel with each other and in a vertical position.

The heat absorbed by the heat collection member 39 is conducted via theheat pipe 37 to the cooling member 11 and radiated as indicated by anarrow AR7 similarly to the aforementioned first embodiment.

The cooling system 33 of the present embodiment has the same effect asthe cooling system 3 of the aforementioned first embodiment and hasanother effect of expanding freedom degrees of disposition because thesubject body W1 is disposed distantly from the heat collection member39. Furthermore, two of the subject bodies W1 may be simultaneouslycooled.

Although the invention has been described above by reference to certainembodiments of the invention, the invention is not limited to theembodiments described above. Modifications and variations of theembodiments described above will occur to those skilled in the art, inlight of the above teachings. For example, a planar subject body hasbeen exemplified, however, any subject body of various shapes can beapplied. Further, if necessary, the shapes of the holder and the heatcollection member can be properly modified. Furthermore, the presentinvention can be applied to various vacuum processing apparatuses suchas a dry-etching apparatus, a sputtering apparatus, a vacuum evaporationapparatus, a cat-CVD apparatus and the like, not limited to the plasmaCVD apparatus.

INDUSTRIAL APPLICABILITY

The present invention provides a cooling for cooling a subject body, thetemperature of which can be effectively regulated by a simpleconstitution.

1. A cooling system for a vacuum processing apparatus, in which asubject body is treated with a vacuum treatment, the cooling systemcomprising: a heat pipe for transfer of heat entering the subject body.2. The cooling system of claim 1, wherein the heat pipe furthercomprises a heat collection member.
 3. The cooling system of claim 2,wherein the heat collection member is surface-treated so as to have alarger radiation coefficient.
 4. A cooling system for a vacuumprocessing apparatus, in which a subject body is treated with a vacuumtreatment, the cooling system comprising: an internal heat conductionpath for transferring heat entering the subject body through the vacuumprocessing apparatus; a heat radiation path for radiation of thetransferred heat to an outside of the vacuum processing apparatus; and aheat conduction path for regulation of quantity of heat transfer betweenthe internal heat conduction path and the heat radiation path.
 5. Thecooling system of claim 4, wherein the heat conduction path comprises awall member and a fluid regulation unit, the wall member isolating theinner heat conduction path and the heat radiation path so as to form aspace, the fluid regulation unit controllably filling a fluid for heatconduction into the space.
 6. The cooling system of claim 5, wherein thefluid comprises gas.
 7. The cooling system of claim 6, wherein the gascomprises one or more gases selected from a group of gases having highheat conduction coefficient.
 8. The cooling system of any one of claimsfrom 5 through 7, wherein the heat conduction path is configured so thatthe heat transfer quantity when the space is vacant is 1/10 or less ofthe heat transfer quantity when the space is filled with the fluid. 9.The cooling system of claim 8, wherein the wall member comprises aninner surface having a radiation coefficient of 0.7 or less.
 10. Thecooling system of claim 8, wherein an inner surface of the wall memberis surface-treated so as to have a radiation coefficient of 0.7 or less.11. The cooling system of any one of claims from 5 through 7, whereinthe inner heat conduction path comprises a heat pipe.